plugins/dap: init + extensions + tests (#455)

tests/test-sources/plugins/dap/dap-python.nix

@@ -0,0 +1,45 @@
+{
+  empty = {
+    plugins.dap.extensions.dap-python.enable = true;
+  };
+
+  example = {
+    plugins.dap.extensions.dap-python = {
+      enable = true;
+
+      customConfigurations = [
+        {
+          type = "python";
+          request = "launch";
+          name = "My custom launch configuration";
+          program = "$\{file}";
+          # ... more options; see https://github.com/microsoft/debugpy/wiki/Debug-configuration-settings
+        }
+      ];
+      resolvePython = ''
+        function()
+          return "/absolute/path/to/python"
+        end
+      '';
+      testRunner = "customTestRunner";
+      testRunners = {
+        customTestRunner = ''
+          function(classname, methodname, opts)
+            local args = {classname, methodname}
+            return 'modulename', args
+          end
+        '';
+      };
+    };
+  };
+
+  default = {
+    plugins.dap.extensions.dap-python = {
+      enable = true;
+
+      console = "integratedTerminal";
+      includeConfigs = true;
+      adapterPythonPath = "python3";
+    };
+  };
+}